1. Field
The present disclosure relates generally to a content-centric network (CCN). More specifically, the present disclosure relates to a system and method for downloading a set of Content Objects using a single named stream in content-centric networks (CCNs).
2. Related Art
The proliferation of the Internet and e-commerce continues to fuel revolutionary changes in the network industry. Today, a significant number of information exchanges, from online movie viewing to daily news delivery, retail sales, and instant messaging, are conducted online. An increasing number of Internet applications are also becoming mobile. However, the current Internet operates on a largely location-based addressing scheme. The two most ubiquitous protocols, Internet Protocol (IP) and Ethernet protocol, are both based on end-host addresses. That is, a consumer of content can only receive the content by explicitly requesting the content from an address (e.g., IP address or Ethernet media access control (MAC) address) that is typically associated with a physical object or location. This restrictive addressing scheme is becoming progressively more inadequate for meeting the ever-changing network demands.
Recently, information-centric network (ICN) architectures have been proposed in the industry where content is directly named and addressed. Content-Centric networking (CCN), an exemplary ICN architecture, brings a new approach to content transport. Instead of viewing network traffic at the application level as end-to-end conversations over which content travels, content is requested or returned based on its unique name, and the network is responsible for routing content from the provider to the consumer. Note that content includes data that can be transported in the communication system, including any form of data such as text, images, video, and/or audio. A consumer and a provider can be a person at a computer or an automated process inside or outside the CCN. A piece of content can refer to the entire content or a respective portion of the content. For example, a newspaper article might be represented by multiple pieces of content embodied as data packets. A piece of content can also be associated with metadata describing or augmenting the piece of content with information such as authentication data, creation date, content owner, etc.
In CCN, names play an important role. More specifically, Content Objects and Interests are identified by their name, which is typically a hierarchically structured variable-length identifier (HSVLI). Interests and Content Objects flow through the network based on their names. When downloading named content, which can be a file library or a web page, the requester often needs to issue an initial set of Interest messages to obtain the catalog of the library or the markup document of the web page. In the case of a web page, upon receiving the markup document, the requester needs to parse the markup document, and then start downloading embedded objects referenced by the markup document. Such a process often requires more than one round-trip time (RTT), thus adding significant latency to the content download process. This problem is similar to the download-latency problem experienced by IP networks.
In the IP world, people have not been satisfied with the performance of Hypertext Transfer Protocol (HTTP), because although very efficient at transferring individual files, HTTP cannot efficiently transfer a large number of small files. However, today's web destinations often include pages with tens of, or more, embedded objects, such as images, cascading style sheet (CSS) files, and external JavaScript files. Loading all these individual files takes time because of all the overhead of separately requesting them and waiting for the TCP (Transmission Control Protocol) sessions to probe the network capacity and ramp up their transmission speed. For example, when requesting web content using HTTP over TCP, the requester typically has to wait for a three-way TCP handshake to be completed to send a GET request before beginning to download the desired HTTP and HTML markup document. Then, after parsing the markup document, the requester can request the individual embedded objects. To reduce such download latency, certain “zero round-trip time” protocols have been developed in the IP setting, such as SPTY™ (registered trademark of Google Inc. of Menlo Park, Calif.) developed by Google. However, no such solutions exist in CCN settings.